Copolymerization of carbon monoxide and olefin with nitrogen containing phosphine ligand catalyst

ABSTRACT

Polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, e.g., ethylene, are produced in the presence of novel catalyst compositions formed from a palladium compound, an anion of a non-hydrohalogenic acid having a pKa less than about 2 and certain bidentate ligands containing atoms of phosphorus and nitrogen.

The invention relates to an improved process of producing copolymers ofcarbon monoxide and at least one olefinically unsaturated hydrocarbon inthe presence of catalyst compositions formed by contacting a palladiumcompound, an anion of a non-hydrohalogenic acid having a pKa less thanabout 2 and certain bidentate ligands which incorporate both phosphorusand nitrogen.

Copolymers of carbon monoxide and ethylenically unsaturatedhydrocarbon(s) are known as polyketones. One class of these polymers isthe class of linear alternating polymers of carbon monoxide andunsaturated hydrocarbon(s) polymerized through the ethylenicunsaturation. For example, when carbon monoxide and ethylene arepolymerized, the polyketone polymer will consist of units of the formula--CO(C₂ H₄)--. Such polymers are typically produced in the presence of acatalyst composition formed from a group VIII metal compound, e.g. apalladium compound, an anion of a non-hydrohalogenic acid having a pkaless than about 2 and a monodentate ligand of phosphorus or a bidentateligand of nitrogen. Although each type of these ligands is useful in theproduction of polyketone copolymers, it would be of advantage to haveadditional ligands available.

SUMMARY OF THE INVENTION

The present invention comprises an improved process of polymerizingcarbon monoxide and at least one olefinically unsaturated hydrocarbon inthe presence of novel catalyst compositions formed from a palladiumcompound, an anion of a non-hydrohalogenic acid having a pKa less thanabout 2 and a bidentate ligand containing atoms of both phosphorus andnitrogen. For simplicity, the ligands are described as a phenylphosphinehaving from 1 to 2 substituents incorporating a nitrogen atom not boundto hydrogen.

DESCRIPTION OF THE INVENTION

In the process of the invention, carbon monoxide is polymerized with atleast one ethylenically unsaturated hydrocarbon. Preferred hydrocarbonsare hydrocarbons of from 2 to 20 carbon atoms inclusive, more preferablyfrom 2 to 10 carbon atoms inclusive. Such hydrocarbons are whollyaliphatic, including α-olefins such as ethylene, propylene, octene-1 anddodecene-1, or are arylalphatic olefins having an aryl substituent on acarbon atom of the ethylenic unsaturation such as styrene,p-methylstyrene and p-ethylstyrene. Preferred embodiments of the processof the invention prepare copolymers of carbon monoxide and ethylene orterpolymers of carbon monoxide, ethylene and a second ethylenicallyunsaturated hydrocarbon, particularly a second α-olefin and mostparticularly propylene.

The molar ration of unsaturated hydrocarbon to carbon monoxide in thepolymerization mixture varies from about 10:1 to about 1:5 butpreferably is from about 5:1 to abut 1:2. When ethylene and a secondunsaturate hydrocarbon are employed to produce a terpolymer with carbonmonoxide, the molar ration of ethylene to the second hydrocarbon is fromabout 400:1 to about 1:1 with ratios from about 100:1 to about 2:1 beingpreferred.

The palladium compound component of the catalyst compositions of theinvention is a palladium salt of a carboxylic acid of up to about 10carbon atoms. In part for reasons of availability, the preferredpalladium carboxylate is palladium acetate although other carboxylatessuch as palladium propionate or palladium hexanoate are suitable.

The palladium compound is employed in conjunction with anon-hydrohalogenic acid having a pKa less than 2. Suitable acids areoxygen-containing acids and are inorganic acids, e.g., perchloric acidor sulfuric acid, or are organic acids including carboxylic acids suchas trichloroacetic acid, difluoroacetic acid and trifluoroacetic acid aswell as sulfonic acids such as para-toluenesulfonic acid,methanesulfonic acid and trifluoromethane sulfonic acid. The acidstrifluoroacetic acid and para-toluenesulfonic acid constitute apreferred class of acids.

The anion is provided in the form of a free acid or alternatively in theform of a slat. Suitable salts include transition metal salts as well asnon-transition metal salts but in general salts of non-noble transitionmetals, i.e., metals of Group IB-Group VIIB of the Periodic Table ofElements are preferred and particularly preferred are copper salts. Inan alternate embodiment, the palladium compound and the anion areintroduced as a single compound such as the complex Pd(CH₃ CN)₂ (O₃S--C₆ H₄ --CH₃)₂ prepared for example by reaction of palladium chloridewith silver para-toluenesulfonate in acetonitrile.

The anion is provide in a quantity from about 0.5 equivalents to about200 equivalents per gram atom of palladium (as the compound), preferablyfrom about 1 equivalent to about 100 equivalents per gram atom ofpalladium.

The bidentate ligand employed in the catalyst composition of theinvention is a bidentate ligand containing phosphorus and at least oneatom of nitrogen. For ease of understanding, the ligand may beconsidered as a nitrogen-containing phosphine derivative wherein atleast one substituent attached to the phosphorus is an organic radicalincorporating at least one nitrogen free from hydrogen substituents.Suitable phenylphosphines are nitrogen containing phenylphosphines ofthe formula

    PA.sub.3

wherein A is selected from phenyl and the nitrogen-containingsubstituent. The nitrogen-containing substituent is a substituent offrom 2 to 20 carbon atoms, inclusive, preferably from 2 to 10 carbonatoms inclusive, containing from 1 to 3 but preferably 1 nitrogen freefrom substitution with hydrogen. The relative position of the nitrogenatom(s) and the phosphorus to which the substituent is attached is notcritical although best results are obtained when from 1 to 3, preferably2, carbon atoms separate the nitrogen moiety from the phosphorus towhich the nitrogen-containing substituent is attached. Preferredsubstituents contain only atoms of carbon, hydrogen and oxygen inaddition to the indicated nitrogen atom(s).

Each nitrogen moiety of each nitrogen-containing substituent is providedin any configuration which results in the nitrogen being free fromhydrogen substitution, such as a cyano radical, an isocyano radical,dialkylamino radicals wherein the alkyls are lower alkyl of up to 6carbon atoms, N,N-dialkylamido radicals wherein the alkyls are loweralkyl of up to 6 carbon atoms, and heterocyclic radicals containing onlyatoms of nitrogen and carbon in the ring such as pyridyl, and triazinyl.

Illustrative of phosphine ligands in which each of the phosphorussubstituents is nitrogen-containing aretris(2-diphenylphosphinoethyl)amine and tris(2-cyanoethyl)phosphine andillustrative ligands in which two of the phosphorus substituents arenitrogen-containing are bis(2-pyridyl)phenylphosphine andbis(2-cyanoethyl)phenylphosphine. The preferred type of phosphineligand, however, is a diphenylphosphine ligand wherein the remainingphosphorus substituent is nitrogen containing. Illustrative of thispreferred class are 1-[2-(diphenylphosphino)ethyl]pyrrole,2-(diphenylphosphino)-N, N-dimethylacetamide,ortho-(diphenylphosphino)-N,N-dimethylaniline,N-[(diphenylphosphino)methyldiethylamine. 2-cyanoethyldiphenylphosphine,2-diphenylphosphino)-1,3,5-triazine and 2-pyridyldiphenylphosphine. The2-cyanoethyl phenyl phosphines and the 2-pyridyl phenyl phosphines forma preferred class.

In the catalyst compositions of the invention the nitrogen-containingbidentate ligand is used in a quantity from about 0.1 mol to abut 100 mlper mol of palladium compound but preferably from about 0.5 mol to about50 mol per mol of palladium compound.

In the catalyst compositions of the invention, it is preferred althoughnot required to additionally provide a quinone. Suitable quinonesinclude anthraquinones and naphthaquinones although benzoquinones arepreferred, particularly 1,4-benzoquinone. The addition of a quinone iswholly optional and amounts of up to about 10,000 mol per mol ofpalladium compound are useful. In the embodiments employing quinone,amounts from about 10 mol to about 5000 mol per mol of palladiumcompound are preferred.

The catalyst composition formed from the palladium compound, the anion,the bidentate ligand and optionally the quinone is employed in catalyticamounts, Quantities of catalyst composition providing from about 1×10⁻⁷to about 1×10⁻³ gram atom of palladium per mol of ethylenicallyunsaturated hydrocarbon are useful with preferred quantities of catalystcomposition providing from about 1×10⁻⁶ to about 1×10⁻⁴ gram atom ofpalladium.

The polymerization process of the invention is conducted underpolymerization conditions in the gas phase or in the presence of aliquid diluent. When diluent is used, a lower alkanol is preferred andparticularly methanol or ethanol. Useful polymerization temperatures arefrom about 20° C. to about 200° C. and in particular from about 30° C.to about 150° C. Suitable pressures are from about 1 bar to about 200bar with pressures from about 20 bar to about 100 bar being preferred.The method of contacting the reactants and catalyst composition is notcritical and is accomplished, for example, by shaking or stirring.Subsequent to reaction the polymer is separated and recovered byconventional means, e.g., filtration or decantation. The polymer maycontain catalyst residues which may be removed, if desired, by treatmentwith a solvent selective for the catalyst residues present.

The polymers of the invention are know polymers of known utility becauseof good mechanical properties. The products find utility as premiumthermoplastics in fibers, films and injection or compression moldingapplications. They find utilization in the production of parts for theautomotive industry, in the manufacture of containers for food anddrinks, as construction and building applications an in similarapplications. The polymer products are modified by mixing or blendingwith other polymeric materials to produce mixtures or blends with variedapplication.

The process and catalyst composition invention are further illustratedby the following Illustrative Embodiments and Comparative Example.

Comparative Example I

A carbon monoxide/ethylene copolymer was prepared by charging to amagnetically stirred autoclave of 250 ml capacity a catalyst solutioncomprising 50 ml of methanol, 0.1 mmol of palladium acetate, 2.0 mmol ofpara-toluenesulfonic acid and 0.3 mmol of triphenylphosphine. Afterremoval of any air present by evacuation, ethylene was introduced untila pressure of 30 bar had been reached and carbon monoxide was addeduntil a pressure of 60 bar had been reached. The contents of theautoclave were then heated to 110° C. After 5 hours the polymerizationwas terminated by cooling to room temperature and releasing thepressure. The polymer product was removed by filtration, washed withmethanol and dried in vacuo at room temperature. The calculatedpolymerization rate was 5 g of copolymer/g Pd/hr.

Illustrative Embodiment I

A copolymer of carbon monoxide and ethylene was produced according tothe procedure of Comparative Example I except that the catalyst solutioncontained 0.2 mmol of palladium acetate and 0.5 mmol of2-cyanoethyldiphenylphosphine instead of 0.3 mmol of triphenylphosphineand the reaction temperature was 80° C. instead of 110° C. Thecalculated polymerization rate was 23.6 g of copolymer/g Pd/hr.

Illustrative Embodiment II

The procedure of Illustrative Embodiment I was repeated except that thereaction temperature was 100° C. instead of 80° C. The calculatedpolymerization rate was 40 g of copolymer/g Pd/hr.

Illustrative Embodiment III

The procedure of Comparative Example I was repeated to prepare a carbonmonoxide/ethylene copolymer except that the catalyst solution contained0.15 mmol of 3-(diphenylphosphino)-N,N-dimethylpropionamide instead ofthe 0.3 mmol of triphenylphosphine and contained 1.0 mmol instead of 2.0mmol of para-toluenesulfonic acid, and the reaction temperature was 105°C. instead of 110° C. The calculated polymerization rate was 28.3 g ofcopolymer/g Pd/hr.

Illustrative Embodiment IV

The procedure of Comparative Example I was repeated to prepare a carbonmonoxide/ethylene copolymer except that the reaction temperature was 80°C. instead of 110° C. and the catalyst solution contained 3.0 mmol of2-pyridyldiphenylphosphine instead of triphenylphosphine and containedan additional 20 mmol of 1,4-benzoquinone. The calculated polymerizationrate was 100 g of copolymer/g Pd/hr.

Illustrative Embodiment V

The procedure of Comparative Example I was repeated to prepare a carbonmonoxide/ethylene copolymer except that the reaction temperature was100° C. instead of 110° C. and the catalyst solution contained 3.0 mmolof bis(2-pyridyl)phenylphosphine instead of triphenylphosphine andadditionally contained 20 ml of 1,4-benzoquinone. the calculatedpolymerization rate was 37.8 g of copolymer/g Pd/hr.

Illustrative Embodiment VI

When the procedure of Illustrative Embodiment I is repeated in theadditional presence of propylene, a yield of a terpolymer of carbonmonoxide, ethylene and propylene will be obtained at a goodpolymerization rate.

Through the use of ¹³ C-NMR analysis, the copolymers of ComparativeExample I and Illustrative Embodiments I-V were shown to have a linearalternating structure consisting of the units --CO(C₂ H₄)--. Each ofthese copolymers has a melting point of 257° C.

What is claimed is:
 1. In the process of producing polymers of carbonmonoxide and at least one ethylenically unsaturated hydrocarbon underpolymerization conditions in the presence of a catalyst compositionformed from a palladium compound, anion of a non-hydrohalogenic acidhaving a pKa less than about 2 and a phosphine ligand, the improvementwherein the ligand is a nitrogen-containing ligand of the formula PA₃wherein A independently is a phenyl substituent or a nitrogen-containingsubstituent of from 2 to 20 carbon atoms and from 1 to 3 nitrogen atoms,and wherein at least one A is the nitrogen-containing substituent, eachnitrogen-containing substituent incorporates at least one nitrogen atomthat is free from substitution with hydrogen, and from 2 to 4 carbonatoms separate each nitrogen atom from the phosphorus atom to which thenitrogen-containing substituent is attached.
 2. The process of claim 1wherein the nitrogen of each nitrogen-containing substituent is providedin a radical selected from cyano, isocyano, dialkylamino, dialkylamidoor heterocyclic having only carbon and nitrogen in the ring.
 3. Theprocess of claim 2 wherein the ligand is a nitrogen-containingdiphenylphosphine ligand.
 4. The process of claim 3 wherein thenitrogen-containing substituent is selected from 2-cyanoethyl or2-pyridyl.
 5. In the process of producing copolymers of carbon monoxideand ethylene under polymerization conditions in the presence of acatalyst composition formed from palladium acetate, anion of an acidselected from trifluoroacetic acid or para-toluenesulfonic acid, and aphosphine ligand, the improvement wherein the ligand is anitrogen-containing ligand of the formula PA₃ wherein A independently isa phenyl substituent or a nitrogen-containing substituent of from 2 to20 carbon atoms and from 1 to 3 nitrogen atoms, and wherein at least oneA is the nitrogen-containing substituent, each nitrogen-containingsubstituent incorporates at least one nitrogen atom that is free fromsubstitution with hydrogen, and from 2 to 4 carbon atoms separate eachnitrogen atom from the phosphorus atom to which the nitrogen-containingsubstituent is attached.
 6. The process of claim 5 wherein eachnitrogen-containing substituent is provided in a radical selected fromcyano, isocyano, dialkylamino, dialkylamido or heterocyclic having onlycarbon and nitrogen is the ring.
 7. The process of claim 6 wherein theligand is a nitrogen-containing diphenylphosphine ligand.
 8. The processof claim 7 wherein the ligand is (2-cyanoethyl)diphenylphosphine.
 9. Theprocess of claim 7 wherein the ligand is 2-pyridyldiphenylphosphine.